Table - Net US Search Ad Revenues By Major Ad Networks

Google raked in $12.79 billion in net US search ad revenues last year, or 73.8% of the total market, eMarketer estimates in its latest forecast. The company’s share will remain constant this year, eMarketer predicts, with revenues rising to $14.39 billion. This is a slight increase to eMarketer’s previous forecast for 2013 and beyond.

For Microsoft, however, the latest estimate of $660 million in US net search ad revenues earned last year and $890 million expected this year represents a dramatic downward revision from the previous predictions of $1.41 billion and $1.84 billion, respectively, based on a new assessment of Microsoft’s likely traffic acquisition costs (TAC). Read the rest at eMarketer.